CA1328115C - Method for making 2,6-naphthalenedicarboxylic acid - Google Patents
Method for making 2,6-naphthalenedicarboxylic acidInfo
- Publication number
- CA1328115C CA1328115C CA 611398 CA611398A CA1328115C CA 1328115 C CA1328115 C CA 1328115C CA 611398 CA611398 CA 611398 CA 611398 A CA611398 A CA 611398A CA 1328115 C CA1328115 C CA 1328115C
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
- C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
- C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups
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- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
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Abstract
METHOD FOR MAKING 2,6-NAPHTHALENEDICARBOXYLIC ACID
ABSTRACT
A method for making 2,6-naphthalenedicarboxylic acid by the oxidation of 2,6-diethylnaphthalene or its oxida-tion derivatives in the presence of a catalyst comprising cobalt, manganese, cerium and bromine components is dis-closed.
ABSTRACT
A method for making 2,6-naphthalenedicarboxylic acid by the oxidation of 2,6-diethylnaphthalene or its oxida-tion derivatives in the presence of a catalyst comprising cobalt, manganese, cerium and bromine components is dis-closed.
Description
` ~3281~
METHOD FOR MAKING 2,6-NAPHTHALENEDICARBOXYLIC ACID
BACKGROtJND OF THE INVENTION
Field of the Invention This invention relates to a method for making 2,6-naphthalenedicarboxylic acid by the oxidation of 2,6~diethylnaphthalene or its oxidation derivative with an oxygen-containing gas under liquid-phase conditions and in the presence of a catalyst comprising metal and bromine components.
Discussion of the Prior Art Fibers and films produced from polyethylenenaphtha-late have improved strength and thermal properties relative to fibers and films produced from polyethylene-terephthalate and are especially useful in applications such as tire cords~ magnetic tape backings and hot-fill containers. However, the use of 2,6-naphthalenedicarbox-ylic acid is inhibited by its relatively high cost, which . 20 is due to the relative unavailability and high cost of the ::~ preferred feedstock, 2,6-dimethylnaphthalene, which can be readily oxidized to 2,6-naphthalenedicarboxylic acid under conditions that are conventional for the oxidation of alk-ylated aromatics -- that is, under liquid phase condi-tions, in a solvent, at elevated temperature and pressure, by an oxygen-containing gas, and in the presence of a cat-alyst comprising cobalt, manganese and bromine components.
It has been proposed to substitute 2,6-diethyl-naphthalene or its oxidation derivative for 2,6-dimethylnaphthalene or its oxidation derivative in the - aforesaid conventional oxidation. For example, Japanese :l examined, accepted patent application 73027318 discloses a method for the production of a naphthalenedicarboxylic by -~, the oxidation of a dialkylnaphthalene having an ethyl or isopropyl group as at least one of the alkyl substituents ` with oxygen in an acetic acid medium at a reaction temper-:~ ature of 90-1~0C and partial oxygen pressure of less than ` ~
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0.5 atmosphere absolute, and in the presence of a catalyst having cobalt, manganese and bromine components. At least ; 2.5 parts of the acetic acid solvent are employed per part of dialkylnaphthalene and the cobalt, manganese and bro-mine components of the catalyst are employed in relative amounts that satisfy the three equations:
(a) x + y ~ 2.0, (b) y > 0.15/x, and (c) 0.2 < z/(x+y) <
10, where x, y and z are the weight percent of cobalt, ~ manganese and bromine, respectively, with respect to the ; 10 weight of dialkylnaphthalene.
In addition, Hirose et al. (Teijin Petrochemical Industries Ltd.), published European Patent Application No. 142719, disclose that the use of the aforesaid conven-tional oxidation conditions for the oxidation of 2,6-diisopropylnaphthalene, or its oxidation derivative, results in an extremely low yield of 2,6-naphthalenedi-carboxylic a~id, which is also of low purity because of the formation of relatively large amounts of undesirable by-products. This published European Patent Application also discloses that variation of the aforesaid conven-tional oxidation, either by the use therein o~ a plurality of oxidation stages in which the reaction temperature is increased stepwise or continuously from a relatively low temperature in an early stage to relatively higher temper-atures in a latter stage, or by maintaining a low concen-tration of 2,6-diisopropylnaphthalene or its oxidation -` derivative in the solvent in the oxidation, did not afford `~ acceptable yields of 2,6-naphthalendicarboxylic acid.
By contrast, the method of the invention disclosed and claimed in Hayaski et al., United Kingdom Patent ~ Application No. 2187744A is a process for the preparation "! of 2,6-naphthalenedicarboxylic acid by the oxidation of , ~
2,6-diisopropylnaphthalene or an oxidized intermediate thereof with molecular oxygen in a lower aliphatic mono-, 35 carboxylic acid solvent containing no more than 30 weight , percent of water, at a reaction temperature of 140-210C
`l and in the presence of a catalyst comprising a water-solu-~` , , : ~
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_3_ ~3~8~ 15 ble cerium salt, a water-soluble cobalt and/or manganese salt and a bromine-containing compound. The molar ratio of diisopropylnaphthalene or its oxidized intermediate-to-the heavy metals of the catalyst is less than 0.4. The atomic ratio of bromine-to-the total heavy metals is 0.001-1, and the usual atomic ratio of the water-soluble salt of cobalt, manganese or their mixture-to-the water soluble salt of cerium is 0.03-30.
Hayaski et al., U.S. Patent No. 4,754,060 discloses a method for producing 2,6-naphthalenedicarboxylic acid together with trimellitic acid by oxidation of 2,6-diisopropylnaphthalene in a lower aliphatic monocar-boxylic acid solvent containing not more than 30 weight percent of water with molecular oxygen at 140-210C and in the presence of a catalyst comprising cobalt, manganese, or a mixture thereof, and bromine. The amount of bromine employed is Q.0001-0.01 in an atomic ratio to the heavy metal catalyst components. The amount of cobalt, manga-nese or a mixture thereof employed is preferably 0.005-0.2 mole to 100 grams of the solvent.
Furthermore, each of Hirose et al., UOS. Patent No.
4,709,088 and European Patent Application No. 142719 dis-closes a method for producing 2,6-naphthalenedicarboxylic acid by the oxidation of 2,6-diisopropylnaphthalene in the presence of a relatively large amount of an oxidation cat-alyst containing a heavy metal element selected from the group consisting of cobalt and manganese and a bromine component, with 0.2 to 10 gram-atoms of the heavy metal ~ element being used per mole of 2,6-diisopropylnaphthalene -- 30 or its oxidation derivative. The oxidation is performed at 140-210C, with the solvent employed at a level of at ; least twice the total weight of 2,6-diisopropyl-.
naphthalene, and preferably with an atomic ratio of ~-I cobalt-to-manganese of 10:90 to 95:5 and with an atomic ratio of bromine to heavy metal components of 0.05:1 to 0.5:1.
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Furthermore, published Japanese patent application Kokai No. 120342/87 discloses a process for oxidizing 2,6-diisopropylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid in a reaction medium con-taining at least 50 weight percent of propionic acid and in the presence of a catalyst comprising (1) a bromine element, (2) cobalt or manganese or a mixture thereof, and (3) an alkali metal element.
Published Japanese patent application Kokai No.
10 120343/87 discloses a process that i5 very similar to that ; of published Japanese patent application KokaL No.
120342/87 but in which the solvent contains at least 50 weight percent of at least one monocarboxylic acid selected from butyric acid, valeric acid and benzoic acid.
Each of Hirose, U.S. Patent No. 4,716,245 and pub-lished Japanese patent application Kokai No. 246143/86 ; discloses a process that is very similar to that of pub-lished Japanese patent application Kokai No. 120342/87 except that at least 70 weight percent of the solvent is acetic acid or propionic acid or a mixture thereof and except that 1.1 to 15 gram atoms of the alkali metal com-ponent of the catalyst must be employed per gram atom of the bromine component of the catalyst.
. ;, OBJECTS OF THE INVENTION
.
~ It is therefore a general object of the present `~ invention to provide an improved method for oxidizing ; 2,6-diethylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid which overcomes the ` 30 aforementioned problems of the prior art.
` More particularly, it is an object of the present ~ invention to provide an improved method for oxidizing ;~ 2,6-diethylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid with an improved yield of , 35 2,6-naphthalenedicarboxylic ; It is another object of the method of the present invention to provide an improved method for oxidizing :.
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2,6-diethylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid of improved purity.
Other objects and advantages of the present invention will become apparent upon reading the following d~tailed description and appended claims.
SUMMARY OF THE INVENTION
-These objects are achieved by the improved method of this invention for producing 2,6-naphthalenedicarboxylic acid comprising: exothermically oxidizing 2,6-diethylnaph~halene or its oxidation derivative as the `~ starting material with an oxygen-containing gas in the liquid phase in a solvent comprising an aliphatic monocar-boxylic acid having, in an oxidation reactor at an ele-vated temperature and pressure and in the presence of an oxidation catalyst comprising cobalt, manganese, bromine and cerium components, wherein the atom ratio of cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst-to-the starting material is in the range of from about 30 to about 10000 mga per gram mole of the ~ starting material, wherein the atom ratio of manganese .~, (calculated as elemental manganese) in the manganese com-`.' ponent of the catalyst-to-cobalt (calculated as elemental cobalt1 in the cobalt component of the catalyst is in the range of from about 0.5 to about 3 mga per mga of cobalt, wherein the atom ratio of bromine (calculated as elemental bromine) in the bromine component of the catalyst-to-total cobalt and manganese (calculated as elemental cobalt and elemental manganese) in the cobalt and manganese conpo-nents of the catalyst is in the range of from about 0.05to about 1 mga per mga of total cobalt and manganese, -.~ wherein the atom ratio of cerium (calculated as elemental cerium) in the cerium component of the catalyst-to-cobalt (calculated as elemental cobalt~ in the co~alt component of the catalyst is in the range of from about 0.025 to `~ about 1.0 mga per mga of cobalt, and wherein heat gener-ated in the oxidation reactor is at least partially dissi-`~`' ~.
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-6- t328~5 pated by vaporization of liquids therein and withdrawal of the resulting vapors from the oxidation reactor.
DETAILED DESCRIPTION OF
THE PREFERRED EMBODIMENTS
The starting material employed in the method of this invention is represented by the following general formula:
. . .
Rl ,~ R2 wherein Rl is selected from the group consisting of IH3 fH3 1 3 1 3 -CH2 , -CO , -CHOH , -CHOOH
and wherein R2 is selected from the group consisting of CH3 ~H3 fH3 IH3 - -CH2, -CO , CHOH , -CHOOH , -COOH and -CHO
, ; and wherein Rl and R2 can be the same or different from each other. Preferably the start;ng material is 2,6-diethylnaphthalene.
`~ Suitable solvents for use in the method of the pres-ent invention for producing 2,6-naphthalenedicarboxylic acid include any aliphatic C2-C6 monocarboxylic acid such as acetic acid, propionic acid, n-butyric acid, isobutyric "' I! acid, n-valeric acid, trimethylacetic acid, and caproic ~ acid and mixtures thereof with water. Preferably, the `~1 solvent is a mixture of acetic acid and water, which more preferably contains from 1 to 30 weight percent of water and most preferably from 2 to 15 weight percent of water, ` the total amount of both that is introduced into the oxi-dation reactor from an external source and that is gener-', ' : ; ~ ........................ .. . . .
.
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ated in situ in the oxidation reaction. Heat generated in the highly exothermic liquid-phase oxidation is dissipated at least partially by vaporization of solvent in the oxi-dation reactor and withdrawal of at least some of the sol-vent from the reactor as a vapor, which is then condensedand recycled to the reactor. In addition, some solvent is withdrawn from the reactor as a liquid in the product stream. After separation of the 2,6-naphthalene dicarbox-ylic acid product from the product stream, at least a por-tion of the mother liquor (solvent) in the resultingproduct stream is recycled to the reactor~ The weight ratio of the total amount of the monocarboxylic acid sol-vent (bot.h fresh and recycle)-to-total amount of 2,6-diethylnaphthalene or its oxidation derivative added during the entire oxidation step in the method of this invention is from about 2:1, preferably from about 3:1, up to about 20:1, preferably up to about 10:1.
l The source of molecular oxygen employed in the method ! of this invention can vary in molecular oxygen content from that of air to oxygen gas. Air is the preferred source of molecular oxygen. Typically, as in liquid-phase oxidati~ns of alkylaromatics such as p-xylene by oxygen and in the presence of a catalyst having heavy metal and ~` bromine components, the oxygen-containing gas fed to the `, 25 oxidation reactor in the method of the present invention provides a pressure of oxygen in the oxidation reactor of from 50 to 300 pounds per square inch gauge and an exhaust ` gas-vapor mixture containing from 0.1 to 15volume percent oxygen and preferably from 2 to 6 volume percent oxygen (measured on a solvent-free basis).
~; The catalyst employed in the method of this invention for producing 2,6-naphthalenedicarboxylic acid comprises i cobalt, manganese, bromine, and cerium components. The atom ratio of cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst-to-the starting mate-;l rial in the liquid-phase oxidation is in the range of from , about 30, preferably from about 60l to about 10000, pref-' ~
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erably to about 500, milligram atoms (mga) per gram mole of the starting material. The atom ratio of manganese (calculated as elemental manganese) in the manganese com-ponent of the catalyst-to-cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst in the liquid-phase oxidation is in the range of from about 0.5, preferably from about 1.0, to about 3, preferably to about 2.5, mga per mga of cobalt. The atom ratio of bromine (calculated as elemental bromine) in the bromine component of the catalyst-to-total cobalt and manganese (calculated as elemental cobalt and elemental manganese) in the cobalt and manganese components of the catalyst is in the range of from about 0.05, preferably from about 0.075, to about 1, preferably to about 0.4, mga per mga of total cobalt and manganese. The atom ratio of cerium (calculated as elemental cerium) in the cerium component of the cata-lyst-to-cobalt Icalculated as elemental cobalt) in the cobalt component of the catalyst is in the range of from about 0.025, preferably from about 0.05, to about 1.0, ~ 20 preferably to about 0.6, mga per mga of cobalt.
- Each of the cobalt, manganese, bromine, and cerium components of the catalyst employed in the method of this invention can be provided in any of its known ionic or combined forms that provide soluble forms of cobalt, man-ganese, bromine, and cerium, respectively, in the solvent in the oxidation reactor. For example, when the solvent ` is an acetic acid medium, cobalt and/or manganese and/or cerium carbonate, acetate, and/or bromide can be employed.
The 0.05:1 to 1:1 bromine-to-total cobalt and manganese milligram atom ratio is provided by a suitable source of bromine. Such bromine sources include elemental bromine (Br2~, or ionic bromides (for example, HBr, NaBr, KBr, :.
NH4Br, etc.), or organic bromides which are known to pro-vide bromide ions at the operating temperature of the oxi-dation (e.g., bromobenzenes, benzylbromide, mono- and ` dibromoacetic acid, bromoacetyl bromide, tetrabromoethane, ethylene-di-bromide, etc.). The total bromine in molecu-, ~1 328~15 lar bromine and ionic bromide is used to determine satis-faction of the elemental bromine-to-total cobalt and manganese milligram atom ratio of 0.05:1 to 1:1. The bromide ion released from the organic bromides at the oxi-S dation operating conditions can be readily determined byknown analytical means. Tetrabromoethane, for example, at operating temperatures of 170 to 225C has been found to yield about 3 effective gram atoms of bromine per gram mole.
In operation, the minimum pressure at which the oxi-dation reactor is maintained is that pressure which will maintain a substantial liquid phase of starting material and at least 70 percent of the solvent. When the solvent is an acetic acid-water mixture, suitable reaction gauge pressures in the oxidation reactor are in the range of from about 0 kg/cm2 to about 35 kg/cm , and typically are in the range of from about 10 kg/cm to about 30 kg/cm .
; The temperature range within the oxidation reactor is gen-erally from about 1~5C, preferably from about 170C, to about ~70C, preferably to about 200C. The solvent resi-dence time in the oxidation reactor is generally from `~ about 20 to about 300 minutes and preférably from about 45 to about 120 minutes ~ . .
The oxidation of the method of this invention can be performed either on a batch, continuous, or semi-continu-, ous mode. In the batch mode, the starting material, sol-; vent and the catalyst components are initially introduced `~ batchwise into the reactor, and the temperature and pres-sure of the reactor contents are then raised to the desired levels therefor for the commencement of the oxida-tion reaction. Air is introduced continuously into the reactor. After commencement of the oxidation reaction--for example, after all of the starting material had been completely introduced into the reactor, the temperature of the reactor contents is raised. In the continuous mode, each of the starting material, air, solvent and the cata-lyst components dissolved in the solvent are continuously .
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. . .
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introduced through a first inlet or set of inlets into a first oxidation reactor where the temperature and pressure are at the desired levels therefor for initiation of the oxidation reaction; and a product stream comprising the 2,6-naphthalene dicarboxylic acid product and catalyst components dissolved in the solvent is withdrawn from the reactor. In the semi-continuous mode, the solvent and the catalyst components are initially introduced batchwise into the reactor~ and then the starting material in sol-vent a~nd air are introduced continuously into the reactor.~fter commencement of the oxidation reaction, the temper-ature of the reactor contents is raised. Typically, the semi-continuous mode is employed for the oxidation of the method of this invention, with the temperature of the reactor contents preferably at about 165-205C when starting material is first introduced and rising to a steady-state temperature of preferably about 170C-270C
as the exothermic oxidation proceeds and with the starting material being introduced preferably at 0O05-1.0 parts per part of solvent by weight per hour preferably for 0.3-4.0 hours.
In each case, the progress of the reaction is moni-tored by measuring oxygen uptake and temperature changes.
`~A run is terminated after oxygen uptake ceases, as evi-`25 denced by a rapid decrease in oxygen uptake--that is, by a rapid increase in the oxygen concentration in the vapor-gas mixture withdrawn from the reactor.
Thereafter, the product stream in the continuous mode or the reactor contents in the batch or semi-continuous mode are cooled at a rate of about 25C-140C per hour to a temperature in the range of from about 35C to about 120C in at least one step and in at least one crystal-lizer such that essentially all of the resulting crude, solid 2,6-naphthalenedicarboxylic acid product is sepa-rated from the product mixture typically by filtration orcentrifugation at a temperature in the range of from about 35C to about 120C. The use of lower temperatures .; .
3 2 ~
results in the recovery of a significantly less pure prod-uct and the use of higher temperatures results in the recovery of less product.
The present invention will be more clearly understood from the following specific example, which involves the oxidation of 2,6-diethylnaphthalene on a semi-continuous basis. The reactor employed was a l-liter reactor equipped with a stirrer, air line, and a line for introduction of air during the oxidation. The temperature of the reactor was controlled by insulated electrical heaters which surrounded the autoclave. The vented gases from the reactor were passed through a condenser, cooled - by dry-ice, and then through instruments which recorded the gaseous flow rate and the concentration of oxygen and carbon oxides in the gas stream. 250 grams of acetic acid solvent and 4.7 grams of cobalt (II) acetate tetrahydrate, 9.3 grams of manganese (II3 aretate tetrahydrate, 0.67 gram of cerium (III) acetate, 1.5 hydrate, and 0.67 gram of sodium bromide components of the catalyst were intro-duced batchwise into the reactor. The reactor was purgedand then pressurized to 400 pounds per square inch gauge with a slow addition of nitrogen gas. The temperature of the reactor contents was raised to 193-197C, the desired level therefor for commencement of the oxidation, and then 170 milliliters of a solution of 0.48 gram of 2,6~diethylnaphthalene per milliliter of acetic acid at a ~` rate of 2-2.5 milliliters per minute and a solution of ., 20.9 volume percent oxygen in nitrogen at a rate of 18 cubic feet per hour were introduced continuously into the reactor.
~` 30 Immediately after the introduction of the 2,6-diethylnaphthalene was completed, (which required 75 minutes). and the introduction of the oxygen-nitrogen solution was continued for about 7.5 minutes longer. The pressure of the reactor was controlled by a research con-trol valve. The rate of oxidation was determined by meas-uring the oxygen content of the vent gas and knowing the flow rate of air through the reactor, and was employed as '. ~
.
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`` 1328~
a measure of the extent of conversion of the reactant~
The reaction was terminated after oxygen uptake had ceased and the oxygen content of the vent gas reached a steady value of 12.0 volume percent, whereupon the flow of air into the reactor was replaced by a flow of nitrogen gas into the reactor. The yield of 2,6- naphthalene-dicarboxylic was measured as 90 mole % based on the amounts of 2,6- naphthalenedicarboxylic acid in the reaction product slurry and reactor wash. The 5 mole per-cent yield of trimellitic acid represents the moles of trimellitic acid identified in the reaction product slurry per mole of 2,6-diethylnaphthalene used.
From the above description, it is apparent that the objects of the present invention have been achieved.
While only certain embodiments have been set forth, alter-,.
native embodiments and various modifications will be .
apparent from the above description to those skilled inthe art. These and other alternatives are considered equivalents and within the spirit and scope o~ the present invention.
, Having described the invention, what is claimed is:
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.
METHOD FOR MAKING 2,6-NAPHTHALENEDICARBOXYLIC ACID
BACKGROtJND OF THE INVENTION
Field of the Invention This invention relates to a method for making 2,6-naphthalenedicarboxylic acid by the oxidation of 2,6~diethylnaphthalene or its oxidation derivative with an oxygen-containing gas under liquid-phase conditions and in the presence of a catalyst comprising metal and bromine components.
Discussion of the Prior Art Fibers and films produced from polyethylenenaphtha-late have improved strength and thermal properties relative to fibers and films produced from polyethylene-terephthalate and are especially useful in applications such as tire cords~ magnetic tape backings and hot-fill containers. However, the use of 2,6-naphthalenedicarbox-ylic acid is inhibited by its relatively high cost, which . 20 is due to the relative unavailability and high cost of the ::~ preferred feedstock, 2,6-dimethylnaphthalene, which can be readily oxidized to 2,6-naphthalenedicarboxylic acid under conditions that are conventional for the oxidation of alk-ylated aromatics -- that is, under liquid phase condi-tions, in a solvent, at elevated temperature and pressure, by an oxygen-containing gas, and in the presence of a cat-alyst comprising cobalt, manganese and bromine components.
It has been proposed to substitute 2,6-diethyl-naphthalene or its oxidation derivative for 2,6-dimethylnaphthalene or its oxidation derivative in the - aforesaid conventional oxidation. For example, Japanese :l examined, accepted patent application 73027318 discloses a method for the production of a naphthalenedicarboxylic by -~, the oxidation of a dialkylnaphthalene having an ethyl or isopropyl group as at least one of the alkyl substituents ` with oxygen in an acetic acid medium at a reaction temper-:~ ature of 90-1~0C and partial oxygen pressure of less than ` ~
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1 32811~
0.5 atmosphere absolute, and in the presence of a catalyst having cobalt, manganese and bromine components. At least ; 2.5 parts of the acetic acid solvent are employed per part of dialkylnaphthalene and the cobalt, manganese and bro-mine components of the catalyst are employed in relative amounts that satisfy the three equations:
(a) x + y ~ 2.0, (b) y > 0.15/x, and (c) 0.2 < z/(x+y) <
10, where x, y and z are the weight percent of cobalt, ~ manganese and bromine, respectively, with respect to the ; 10 weight of dialkylnaphthalene.
In addition, Hirose et al. (Teijin Petrochemical Industries Ltd.), published European Patent Application No. 142719, disclose that the use of the aforesaid conven-tional oxidation conditions for the oxidation of 2,6-diisopropylnaphthalene, or its oxidation derivative, results in an extremely low yield of 2,6-naphthalenedi-carboxylic a~id, which is also of low purity because of the formation of relatively large amounts of undesirable by-products. This published European Patent Application also discloses that variation of the aforesaid conven-tional oxidation, either by the use therein o~ a plurality of oxidation stages in which the reaction temperature is increased stepwise or continuously from a relatively low temperature in an early stage to relatively higher temper-atures in a latter stage, or by maintaining a low concen-tration of 2,6-diisopropylnaphthalene or its oxidation -` derivative in the solvent in the oxidation, did not afford `~ acceptable yields of 2,6-naphthalendicarboxylic acid.
By contrast, the method of the invention disclosed and claimed in Hayaski et al., United Kingdom Patent ~ Application No. 2187744A is a process for the preparation "! of 2,6-naphthalenedicarboxylic acid by the oxidation of , ~
2,6-diisopropylnaphthalene or an oxidized intermediate thereof with molecular oxygen in a lower aliphatic mono-, 35 carboxylic acid solvent containing no more than 30 weight , percent of water, at a reaction temperature of 140-210C
`l and in the presence of a catalyst comprising a water-solu-~` , , : ~
. . .
,, !
:`, : ;-.. ~ `
~ , . .. .
: ' :
_3_ ~3~8~ 15 ble cerium salt, a water-soluble cobalt and/or manganese salt and a bromine-containing compound. The molar ratio of diisopropylnaphthalene or its oxidized intermediate-to-the heavy metals of the catalyst is less than 0.4. The atomic ratio of bromine-to-the total heavy metals is 0.001-1, and the usual atomic ratio of the water-soluble salt of cobalt, manganese or their mixture-to-the water soluble salt of cerium is 0.03-30.
Hayaski et al., U.S. Patent No. 4,754,060 discloses a method for producing 2,6-naphthalenedicarboxylic acid together with trimellitic acid by oxidation of 2,6-diisopropylnaphthalene in a lower aliphatic monocar-boxylic acid solvent containing not more than 30 weight percent of water with molecular oxygen at 140-210C and in the presence of a catalyst comprising cobalt, manganese, or a mixture thereof, and bromine. The amount of bromine employed is Q.0001-0.01 in an atomic ratio to the heavy metal catalyst components. The amount of cobalt, manga-nese or a mixture thereof employed is preferably 0.005-0.2 mole to 100 grams of the solvent.
Furthermore, each of Hirose et al., UOS. Patent No.
4,709,088 and European Patent Application No. 142719 dis-closes a method for producing 2,6-naphthalenedicarboxylic acid by the oxidation of 2,6-diisopropylnaphthalene in the presence of a relatively large amount of an oxidation cat-alyst containing a heavy metal element selected from the group consisting of cobalt and manganese and a bromine component, with 0.2 to 10 gram-atoms of the heavy metal ~ element being used per mole of 2,6-diisopropylnaphthalene -- 30 or its oxidation derivative. The oxidation is performed at 140-210C, with the solvent employed at a level of at ; least twice the total weight of 2,6-diisopropyl-.
naphthalene, and preferably with an atomic ratio of ~-I cobalt-to-manganese of 10:90 to 95:5 and with an atomic ratio of bromine to heavy metal components of 0.05:1 to 0.5:1.
~ . :
. , . . .
~328il~
Furthermore, published Japanese patent application Kokai No. 120342/87 discloses a process for oxidizing 2,6-diisopropylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid in a reaction medium con-taining at least 50 weight percent of propionic acid and in the presence of a catalyst comprising (1) a bromine element, (2) cobalt or manganese or a mixture thereof, and (3) an alkali metal element.
Published Japanese patent application Kokai No.
10 120343/87 discloses a process that i5 very similar to that ; of published Japanese patent application KokaL No.
120342/87 but in which the solvent contains at least 50 weight percent of at least one monocarboxylic acid selected from butyric acid, valeric acid and benzoic acid.
Each of Hirose, U.S. Patent No. 4,716,245 and pub-lished Japanese patent application Kokai No. 246143/86 ; discloses a process that is very similar to that of pub-lished Japanese patent application Kokai No. 120342/87 except that at least 70 weight percent of the solvent is acetic acid or propionic acid or a mixture thereof and except that 1.1 to 15 gram atoms of the alkali metal com-ponent of the catalyst must be employed per gram atom of the bromine component of the catalyst.
. ;, OBJECTS OF THE INVENTION
.
~ It is therefore a general object of the present `~ invention to provide an improved method for oxidizing ; 2,6-diethylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid which overcomes the ` 30 aforementioned problems of the prior art.
` More particularly, it is an object of the present ~ invention to provide an improved method for oxidizing ;~ 2,6-diethylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid with an improved yield of , 35 2,6-naphthalenedicarboxylic ; It is another object of the method of the present invention to provide an improved method for oxidizing :.
'' ..
...
, _5_ ~328~
2,6-diethylnaphthalene or its oxidation derivative to 2,6-naphthalenedicarboxylic acid of improved purity.
Other objects and advantages of the present invention will become apparent upon reading the following d~tailed description and appended claims.
SUMMARY OF THE INVENTION
-These objects are achieved by the improved method of this invention for producing 2,6-naphthalenedicarboxylic acid comprising: exothermically oxidizing 2,6-diethylnaph~halene or its oxidation derivative as the `~ starting material with an oxygen-containing gas in the liquid phase in a solvent comprising an aliphatic monocar-boxylic acid having, in an oxidation reactor at an ele-vated temperature and pressure and in the presence of an oxidation catalyst comprising cobalt, manganese, bromine and cerium components, wherein the atom ratio of cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst-to-the starting material is in the range of from about 30 to about 10000 mga per gram mole of the ~ starting material, wherein the atom ratio of manganese .~, (calculated as elemental manganese) in the manganese com-`.' ponent of the catalyst-to-cobalt (calculated as elemental cobalt1 in the cobalt component of the catalyst is in the range of from about 0.5 to about 3 mga per mga of cobalt, wherein the atom ratio of bromine (calculated as elemental bromine) in the bromine component of the catalyst-to-total cobalt and manganese (calculated as elemental cobalt and elemental manganese) in the cobalt and manganese conpo-nents of the catalyst is in the range of from about 0.05to about 1 mga per mga of total cobalt and manganese, -.~ wherein the atom ratio of cerium (calculated as elemental cerium) in the cerium component of the catalyst-to-cobalt (calculated as elemental cobalt~ in the co~alt component of the catalyst is in the range of from about 0.025 to `~ about 1.0 mga per mga of cobalt, and wherein heat gener-ated in the oxidation reactor is at least partially dissi-`~`' ~.
: :, :`
~ ~ , :
`:
-6- t328~5 pated by vaporization of liquids therein and withdrawal of the resulting vapors from the oxidation reactor.
DETAILED DESCRIPTION OF
THE PREFERRED EMBODIMENTS
The starting material employed in the method of this invention is represented by the following general formula:
. . .
Rl ,~ R2 wherein Rl is selected from the group consisting of IH3 fH3 1 3 1 3 -CH2 , -CO , -CHOH , -CHOOH
and wherein R2 is selected from the group consisting of CH3 ~H3 fH3 IH3 - -CH2, -CO , CHOH , -CHOOH , -COOH and -CHO
, ; and wherein Rl and R2 can be the same or different from each other. Preferably the start;ng material is 2,6-diethylnaphthalene.
`~ Suitable solvents for use in the method of the pres-ent invention for producing 2,6-naphthalenedicarboxylic acid include any aliphatic C2-C6 monocarboxylic acid such as acetic acid, propionic acid, n-butyric acid, isobutyric "' I! acid, n-valeric acid, trimethylacetic acid, and caproic ~ acid and mixtures thereof with water. Preferably, the `~1 solvent is a mixture of acetic acid and water, which more preferably contains from 1 to 30 weight percent of water and most preferably from 2 to 15 weight percent of water, ` the total amount of both that is introduced into the oxi-dation reactor from an external source and that is gener-', ' : ; ~ ........................ .. . . .
.
-7~ 1 3 2 ~
ated in situ in the oxidation reaction. Heat generated in the highly exothermic liquid-phase oxidation is dissipated at least partially by vaporization of solvent in the oxi-dation reactor and withdrawal of at least some of the sol-vent from the reactor as a vapor, which is then condensedand recycled to the reactor. In addition, some solvent is withdrawn from the reactor as a liquid in the product stream. After separation of the 2,6-naphthalene dicarbox-ylic acid product from the product stream, at least a por-tion of the mother liquor (solvent) in the resultingproduct stream is recycled to the reactor~ The weight ratio of the total amount of the monocarboxylic acid sol-vent (bot.h fresh and recycle)-to-total amount of 2,6-diethylnaphthalene or its oxidation derivative added during the entire oxidation step in the method of this invention is from about 2:1, preferably from about 3:1, up to about 20:1, preferably up to about 10:1.
l The source of molecular oxygen employed in the method ! of this invention can vary in molecular oxygen content from that of air to oxygen gas. Air is the preferred source of molecular oxygen. Typically, as in liquid-phase oxidati~ns of alkylaromatics such as p-xylene by oxygen and in the presence of a catalyst having heavy metal and ~` bromine components, the oxygen-containing gas fed to the `, 25 oxidation reactor in the method of the present invention provides a pressure of oxygen in the oxidation reactor of from 50 to 300 pounds per square inch gauge and an exhaust ` gas-vapor mixture containing from 0.1 to 15volume percent oxygen and preferably from 2 to 6 volume percent oxygen (measured on a solvent-free basis).
~; The catalyst employed in the method of this invention for producing 2,6-naphthalenedicarboxylic acid comprises i cobalt, manganese, bromine, and cerium components. The atom ratio of cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst-to-the starting mate-;l rial in the liquid-phase oxidation is in the range of from , about 30, preferably from about 60l to about 10000, pref-' ~
' ' ' . ' ;' ' ' ::
. ' .
.
.
1328~ ~
erably to about 500, milligram atoms (mga) per gram mole of the starting material. The atom ratio of manganese (calculated as elemental manganese) in the manganese com-ponent of the catalyst-to-cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst in the liquid-phase oxidation is in the range of from about 0.5, preferably from about 1.0, to about 3, preferably to about 2.5, mga per mga of cobalt. The atom ratio of bromine (calculated as elemental bromine) in the bromine component of the catalyst-to-total cobalt and manganese (calculated as elemental cobalt and elemental manganese) in the cobalt and manganese components of the catalyst is in the range of from about 0.05, preferably from about 0.075, to about 1, preferably to about 0.4, mga per mga of total cobalt and manganese. The atom ratio of cerium (calculated as elemental cerium) in the cerium component of the cata-lyst-to-cobalt Icalculated as elemental cobalt) in the cobalt component of the catalyst is in the range of from about 0.025, preferably from about 0.05, to about 1.0, ~ 20 preferably to about 0.6, mga per mga of cobalt.
- Each of the cobalt, manganese, bromine, and cerium components of the catalyst employed in the method of this invention can be provided in any of its known ionic or combined forms that provide soluble forms of cobalt, man-ganese, bromine, and cerium, respectively, in the solvent in the oxidation reactor. For example, when the solvent ` is an acetic acid medium, cobalt and/or manganese and/or cerium carbonate, acetate, and/or bromide can be employed.
The 0.05:1 to 1:1 bromine-to-total cobalt and manganese milligram atom ratio is provided by a suitable source of bromine. Such bromine sources include elemental bromine (Br2~, or ionic bromides (for example, HBr, NaBr, KBr, :.
NH4Br, etc.), or organic bromides which are known to pro-vide bromide ions at the operating temperature of the oxi-dation (e.g., bromobenzenes, benzylbromide, mono- and ` dibromoacetic acid, bromoacetyl bromide, tetrabromoethane, ethylene-di-bromide, etc.). The total bromine in molecu-, ~1 328~15 lar bromine and ionic bromide is used to determine satis-faction of the elemental bromine-to-total cobalt and manganese milligram atom ratio of 0.05:1 to 1:1. The bromide ion released from the organic bromides at the oxi-S dation operating conditions can be readily determined byknown analytical means. Tetrabromoethane, for example, at operating temperatures of 170 to 225C has been found to yield about 3 effective gram atoms of bromine per gram mole.
In operation, the minimum pressure at which the oxi-dation reactor is maintained is that pressure which will maintain a substantial liquid phase of starting material and at least 70 percent of the solvent. When the solvent is an acetic acid-water mixture, suitable reaction gauge pressures in the oxidation reactor are in the range of from about 0 kg/cm2 to about 35 kg/cm , and typically are in the range of from about 10 kg/cm to about 30 kg/cm .
; The temperature range within the oxidation reactor is gen-erally from about 1~5C, preferably from about 170C, to about ~70C, preferably to about 200C. The solvent resi-dence time in the oxidation reactor is generally from `~ about 20 to about 300 minutes and preférably from about 45 to about 120 minutes ~ . .
The oxidation of the method of this invention can be performed either on a batch, continuous, or semi-continu-, ous mode. In the batch mode, the starting material, sol-; vent and the catalyst components are initially introduced `~ batchwise into the reactor, and the temperature and pres-sure of the reactor contents are then raised to the desired levels therefor for the commencement of the oxida-tion reaction. Air is introduced continuously into the reactor. After commencement of the oxidation reaction--for example, after all of the starting material had been completely introduced into the reactor, the temperature of the reactor contents is raised. In the continuous mode, each of the starting material, air, solvent and the cata-lyst components dissolved in the solvent are continuously .
:;:~ ' . ' ' '- ' - .
. . .
1328~
introduced through a first inlet or set of inlets into a first oxidation reactor where the temperature and pressure are at the desired levels therefor for initiation of the oxidation reaction; and a product stream comprising the 2,6-naphthalene dicarboxylic acid product and catalyst components dissolved in the solvent is withdrawn from the reactor. In the semi-continuous mode, the solvent and the catalyst components are initially introduced batchwise into the reactor~ and then the starting material in sol-vent a~nd air are introduced continuously into the reactor.~fter commencement of the oxidation reaction, the temper-ature of the reactor contents is raised. Typically, the semi-continuous mode is employed for the oxidation of the method of this invention, with the temperature of the reactor contents preferably at about 165-205C when starting material is first introduced and rising to a steady-state temperature of preferably about 170C-270C
as the exothermic oxidation proceeds and with the starting material being introduced preferably at 0O05-1.0 parts per part of solvent by weight per hour preferably for 0.3-4.0 hours.
In each case, the progress of the reaction is moni-tored by measuring oxygen uptake and temperature changes.
`~A run is terminated after oxygen uptake ceases, as evi-`25 denced by a rapid decrease in oxygen uptake--that is, by a rapid increase in the oxygen concentration in the vapor-gas mixture withdrawn from the reactor.
Thereafter, the product stream in the continuous mode or the reactor contents in the batch or semi-continuous mode are cooled at a rate of about 25C-140C per hour to a temperature in the range of from about 35C to about 120C in at least one step and in at least one crystal-lizer such that essentially all of the resulting crude, solid 2,6-naphthalenedicarboxylic acid product is sepa-rated from the product mixture typically by filtration orcentrifugation at a temperature in the range of from about 35C to about 120C. The use of lower temperatures .; .
3 2 ~
results in the recovery of a significantly less pure prod-uct and the use of higher temperatures results in the recovery of less product.
The present invention will be more clearly understood from the following specific example, which involves the oxidation of 2,6-diethylnaphthalene on a semi-continuous basis. The reactor employed was a l-liter reactor equipped with a stirrer, air line, and a line for introduction of air during the oxidation. The temperature of the reactor was controlled by insulated electrical heaters which surrounded the autoclave. The vented gases from the reactor were passed through a condenser, cooled - by dry-ice, and then through instruments which recorded the gaseous flow rate and the concentration of oxygen and carbon oxides in the gas stream. 250 grams of acetic acid solvent and 4.7 grams of cobalt (II) acetate tetrahydrate, 9.3 grams of manganese (II3 aretate tetrahydrate, 0.67 gram of cerium (III) acetate, 1.5 hydrate, and 0.67 gram of sodium bromide components of the catalyst were intro-duced batchwise into the reactor. The reactor was purgedand then pressurized to 400 pounds per square inch gauge with a slow addition of nitrogen gas. The temperature of the reactor contents was raised to 193-197C, the desired level therefor for commencement of the oxidation, and then 170 milliliters of a solution of 0.48 gram of 2,6~diethylnaphthalene per milliliter of acetic acid at a ~` rate of 2-2.5 milliliters per minute and a solution of ., 20.9 volume percent oxygen in nitrogen at a rate of 18 cubic feet per hour were introduced continuously into the reactor.
~` 30 Immediately after the introduction of the 2,6-diethylnaphthalene was completed, (which required 75 minutes). and the introduction of the oxygen-nitrogen solution was continued for about 7.5 minutes longer. The pressure of the reactor was controlled by a research con-trol valve. The rate of oxidation was determined by meas-uring the oxygen content of the vent gas and knowing the flow rate of air through the reactor, and was employed as '. ~
.
'' '.
`` 1328~
a measure of the extent of conversion of the reactant~
The reaction was terminated after oxygen uptake had ceased and the oxygen content of the vent gas reached a steady value of 12.0 volume percent, whereupon the flow of air into the reactor was replaced by a flow of nitrogen gas into the reactor. The yield of 2,6- naphthalene-dicarboxylic was measured as 90 mole % based on the amounts of 2,6- naphthalenedicarboxylic acid in the reaction product slurry and reactor wash. The 5 mole per-cent yield of trimellitic acid represents the moles of trimellitic acid identified in the reaction product slurry per mole of 2,6-diethylnaphthalene used.
From the above description, it is apparent that the objects of the present invention have been achieved.
While only certain embodiments have been set forth, alter-,.
native embodiments and various modifications will be .
apparent from the above description to those skilled inthe art. These and other alternatives are considered equivalents and within the spirit and scope o~ the present invention.
, Having described the invention, what is claimed is:
~.
~ ,, ~ 25 ,."
.- ~
.
Claims (10)
1. A method for producing 2,6-naphthalene dicarbox-ylic acid comprising: exothermically oxidizing
2,6-diethylnaphthalene or its oxidation derivative as the starting material with an oxygen-containing gas in the liquid-phase in a solvent comprising an aliphatic monocar-boxylic acid, in an oxidation reactor at a temperature in the range of about 165°C to about 270°C, and at a pressure in the range of about 0 to about 35kg/cm2 gauge and in the presence of an oxidation catalyst comprising cobalt, manganese, bromine and cerium components, wherein the atom ratio of cobalt (calculated as elemental cobalt) in the cobalt component of the cata-lyst-to-the starting material in the liquid-phase oxida-tion is in the range of from about 30 to about 10000 mga per gram mole of the starting material, wherein the atom ratio of manganese (calculated as elemental manganese) in the manganese component of the catalyst-to-cobalt (calcu-lated as elemental cobalt) in the cobalt component of the catalyst is in the range of from about 0.5 to about 3 mga per mga of cobalt, wherein the atom ratio of bromine (cal-culated as elemental bromine) in the bromine component of the catalyst-to-total cobalt and manganese (calculated as elemental cobalt and elemental manganese) in the cobalt and manganese components of the catalyst is in the range of from about 0.05 to about 1 mga per mga of total cobalt and manganese, and wherein the atom ratio of cerium (cal-culated as elemental cerium) in the cerium component of the catalyst-to-cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst is in the range of from about 0.025 to about 1.0 mga per mga of cobalt, wherein heat generated in the oxidation reactor is at least partially dissipated by vaporization of liquids therein and withdrawal of the resulting vapors from the oxidation reactor, and wherein oxygen is maintained at a concentration level in the oxidation reactor such that the concentration of oxygen in the aforesaid withdrawn vapors is in the range of from about 0.1 to about 15 volume per-cent.
2. The method of Claim 1 wherein the atom ratio of cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst-to-the starting material in the liquid-phase oxidation is in the range of from about 60 to about 500 mga per gram mole of the starting material.
2. The method of Claim 1 wherein the atom ratio of cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst-to-the starting material in the liquid-phase oxidation is in the range of from about 60 to about 500 mga per gram mole of the starting material.
3. The method of Claim 1 wherein the atom ratio of manganese (calculated as elemental manganese) in the man-ganese component of the catalyst-to-cobalt (calculated as elemental cobalt) in the cobalt component of the catalyst is in the range of from about 1.0 to about 2.5 mga per mga of cobalt.
4. The method of Claim 1 wherein the atom ratio of bromine (calculated as elemental bromine) in the bromine (calculated as elemental bromine) in the bromine component of the catalyst-to-total cobalt and manganese (calculated as elemental cobalt and elemental manganese) in the cobalt and manganese components of the catalyst is in the range of from about 0.075 to about 0.4 mga per mga of total cobalt and manganese.
5. The method of Claim 1 wherein the atom ratio of cerium (calculated as elemental cerium) in the cerium com-ponent of the catalyst-to-cobalt (calculated as elemental cobalt) in the cerium component of the catalyst is in the range of from about 0.05 to about 0.6 mga per mga of cobalt.
6. The method of Claim 1 wherein the oxygen is main-tained at a concentration level in the reactor such that the concentration of oxygen in the withdrawn vapors is in the range of from about 2 to about 6 volume percent.
7. The method of Claim 1 wherein the oxidation is performed at a temperature in the range of from about 170°C to about 200°C.
8. The method of Claim 1 wherein the solvent is a mixture of acetic acid and from about 1 to about 30 weight percent of water, based on the weight of acetic acid.
9. The method of Claim 8 wherein the solvent is a mixture of acetic acid and from about 2 to about 15 weight percent of water, based on the weight of acetic acid.
10. The method of Claim 1 wherein the pressure is in the range of from about 10 to about 30 kg/cm2 gauge.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US25083788A | 1988-09-28 | 1988-09-28 | |
| US250,837 | 1988-09-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1328115C true CA1328115C (en) | 1994-03-29 |
Family
ID=22949364
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 611398 Expired - Fee Related CA1328115C (en) | 1988-09-28 | 1989-09-14 | Method for making 2,6-naphthalenedicarboxylic acid |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0361840B1 (en) |
| JP (1) | JP2736129B2 (en) |
| CA (1) | CA1328115C (en) |
| DE (1) | DE68922361T2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5144066A (en) * | 1990-06-26 | 1992-09-01 | Nippon Shokubai Co., Ltd. | Method of producing naphthalenedicarboxylic acids and diaryldicarboxylic acids |
| US6114575A (en) * | 1997-03-25 | 2000-09-05 | Bp Amoco Corporation | Process for preparing 2,6-naphthalenedicarboxylic acid |
| KR100623849B1 (en) * | 1998-12-24 | 2006-12-19 | 에스케이케미칼주식회사 | Method for producing 2,6-naphthalenedicarboxylic acid |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB910484A (en) * | 1957-11-22 | 1962-11-14 | Mid Century Corp | Production of carboxylic acids |
| CA1303059C (en) * | 1986-03-14 | 1992-06-09 | Toshiharu Matsuda | Process for producing 2,6-naphthalenedicarboxylic acid by oxidizing 2,6-diisopropylnaphthalene |
| US4792621A (en) * | 1986-07-28 | 1988-12-20 | Amoco Corporation | Method for continuous production of aromatic carboxylic acid |
| JPH01160943A (en) * | 1987-12-17 | 1989-06-23 | Sumikin Chem Co Ltd | Production of naphthalenedicarboxylic acid |
-
1989
- 1989-09-14 CA CA 611398 patent/CA1328115C/en not_active Expired - Fee Related
- 1989-09-26 DE DE1989622361 patent/DE68922361T2/en not_active Expired - Fee Related
- 1989-09-26 EP EP19890309750 patent/EP0361840B1/en not_active Expired - Lifetime
- 1989-09-27 JP JP1249364A patent/JP2736129B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0361840A3 (en) | 1991-09-18 |
| DE68922361D1 (en) | 1995-06-01 |
| EP0361840B1 (en) | 1995-04-26 |
| JP2736129B2 (en) | 1998-04-02 |
| JPH02188554A (en) | 1990-07-24 |
| DE68922361T2 (en) | 1995-11-02 |
| EP0361840A2 (en) | 1990-04-04 |
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